1. Field of the Invention
The present invention pertains to user interfaces, and, in particular, to self-conforming, compact user interfaces that have a pivot coupling with a port so that both the coupling and port rotate together.
2. Description of the Related Art
A variety of delivery systems are known that provide gas at positive pressure for consumption by a patient. The uses and applications of such systems vary. Some such systems have been developed for the treatment of sleep apnea and other sleep related disorders.
Sleep apnea syndrome results in episodic upper airway obstruction during sleep. As a consequence, there is repeated interruption of sleep in the patient. Positive airway pressure (PAP) devices have been developed to treat this disorder. A typical PAP device comprises a flow generator (e.g., a blower) that delivers gas via a delivery conduit to a user interface, such as a mask. It is also known to deliver the PAP as a continuous positive airway pressure (CPAP), a variable airway pressure, such as a bi-level pressure that varies with the patient's respiratory cycle (Bi-PAP), or an auto-titrating pressure that varies with the monitored condition of the patient. Pressure support therapies are also provided to treat other medical and respiratory disorders, such as Cheynes-Stokes respiration, congestive heart failure, and stroke.
Much development has revolved around user interfaces. In order to be effective, a user interface must be both comfortable and provide an adequate seal. If the user interface is not comfortable, patient compliance will be low. Yet, if the user interface does not provide an adequate seal, the gas will not be appropriately delivered to the user. Often patients use these devices while they are asleep. It is not uncommon for the user to be restless or move around. In this application, the goal of providing a user interface that is comfortable is at odds with the goal of maintaining a seal.
One device exemplary of the state of the art is disclosed in U.S. Patent Application No. US-2003-0075180 (“the '180 application”). The user interface disclosed in this application has a rigid shell that supports a cushion and a fixed coupling with a coupling conduit. The coupling conduit extends generally upwardly from the shell along the bridge of the user's nose towards the user's forehead and includes a ball-and-socket joint to provide the coupling conduit with a limited range of motion. As the user moves their head, the ball-and socket joint will pivot so that the user interface will remain properly sealed to the face of the user. The coupling conduit is attached to a gas delivery conduit which, in turn, is connected to a ventilator to apply positive pressure. Returning to the patient interface, the shell is connected to the cushion by a retaining clip. The retaining clip fits into a channel formed on the shell. A corresponding retaining lip extends about the periphery of the cushion thereby defining the channel about the periphery of the cushion. The retaining clip engages the channel about the cushion. In other words, the retaining clip and the retaining lip on the cushion interlock in a c-shaped cross-section. A plurality of integral detents formed on the retaining clip fit through slots in the shell and hold the retaining clip in place. To secure the user interface in place to the user, the shell includes an extension portion that extends upward from the mask towards the user's forehead. The extension portion is connected to a flexible horizontal strap that engages the sides and the rear rather than the front of the user's head so that the flexible horizontal strap is spaced from the user's forehead to reduce pressure in this region.
Although the device disclosed in the '180 application is adequate for its intended purpose, it also has several drawbacks as well. Even though the ball-and-socket joint provides some range of motion, it is limited such that the coupling conduit must still be generally directed upward in the direction of the user's forehead. This device is ineffective at redirecting the coupling conduit in any other general direction. Since users often use these interfaces while they are asleep, it would be desirable to have a maximum degree of freedom so that the user can freely move their head, or even turn over in bed, without affecting the seal between the user interface and the user.
Another drawback to this device is that it secures the patient interface with a flexible horizontal strap that contacts the sides of the user's head rather than the user's forehead. Although presented as an advantage, patients often wear these user interfaces while they are asleep. Many such users sleep on their side for at least a portion of the night. When pressure from a pillow or bed is applied to the side of the user's head, the flexibility of this design combined with the lack of forehead support will allow the user interface to shift on the user's face and may become uncomfortable or break the seal between the user interface and the user compromising both comfort and the seal.
This device has yet another drawback. The cushion is secured to the mask with a retaining clip that engages the retaining lip of the shell in a c-shaped interlocking configuration. However, if a tensile force is applied to the shell on one end and the cushion on the other, the cushion is likely to pull free of the retaining clip thus requiring reattachment. Because user interfaces experience a great deal of abuse when used, it is undesirable to have a cushion that can be easily pulled free of the shell. In addition, this device does not disclose a pressure port to monitor the internal pressure within the patient interface.
Other patient interfaces have been suggested to advance the art. For instance the device described in U.S. Pat. No. 6,467,483 (“the '483 patent”) discloses a patient interface that has a shell attached between a flexible cushion and a coupling conduit. The shell includes a shell body and a rigid support that supports a forehead pad. Together, the cushion and rigid support hold the user interface on the face of the user. The distance between the rigid support and the shell body may be adjusted to accommodate the unique facial characteristics of different users. Another feature of note is that in this device the coupling conduit is a rotatable elbow that provides 360 degrees of rotation thereby allowing the gas delivery conduit to be directed in a multitude of directions from the patient interface rather than being limited to any one direction. Further unlike the device disclosed in the '180 application, the shell of this user interface has a port for the attachment of a variety of items when access to the interior of the user interface is desired such as a pressure port.
Although the device described in the '483 patent has advanced the art, it can still be further improved upon. Because the coupling conduit is free to rotate 360 degrees, it may become tangled with the port that extends from a fixed location on the shell. If the user repeatedly spins the coupling conduit, each rotation may further tangle the coupling conduit with whatever is connected to the port. In addition, the forehead pad is supported by a rigid support. Even though the distance between the rigid support and the shell body may be adjusted, this may still not be comfortable for some users. Some users may have facial characteristics that are not precisely suited to the contours of this rigid extension. In this circumstance, the patient interface may not fit properly or may simply be uncomfortable.
Another drawback to the device disclosed in the '483 patent is that the coupling conduit is an elbow-type connector that extends a substantial distance away from the shell body. This coupling conduit may be more likely to become tangled with other items in the user's environment. In addition, many users of patient interface devices are self-conscious about wearing the device and would prefer a compact, low-profile user interface. Having a coupling conduit that extends a substantial distance away from the shell body is likely to be deemed undesirable by many users.
Accordingly, it would be desirable to have a patient interface that reduces the likelihood that the pressure port and gas delivery conduit will become tangled during use. It would also be desirable to have a patient interface that can be securely mounted to multiple different users. Further, it would be desirable to have a patient interface that is easy to assemble but also reduces the possibility of the cushion becoming disconnected from the shell during use.